How to use the high and low voltage clamp ammeter to quickly find the leakage fault point
A new method for quickly finding the leakage fault point is the four-wire single-fire clamp meter method. The search steps are as follows: first disconnect the main circuit breaker in the station area, connect the low-voltage four-wire outgoing line (including the neutral wire) in parallel in the station area, then connect one phase of the power supply, and then use the high and low voltage clamp ammeter to measure phase by phase and step by step to determine the leakage fault point. The four-wire single-fire clamp meter method has a small workload, quick fault point finding, and small safety risks.
1. Head-end measurement judgment. First cut off the leakage circuit of the power distribution room (box). After verifying that there is no voltage, remove the three-phase fuse zero of the circuit A, B, and C and untie the neutral wire (N) (if there is no fuse, untie the outgoing wires of the circuit, including the neutral wire, and mark the neutral wire and phase sequence of other phases). Connect the four wires in parallel, take any phase live wire and send power, so that all four wires are energized by single fire. At this time, high and low voltage clamp ammeters can be used to measure the four wires respectively. If the measured Gan line shows a large current value, while the other three lines have a small or zero value, it means that a serious leakage fault has occurred with a large current value. If you check the four-wire measurement, there are not small readings, indicating that each phase has different degrees of leakage. No matter what the situation is, according to the principle that the current value is large first and then small, find the leakage fault point step by step.
2. Confirm the first shot again. After the leakage fault phase has been judged and confirmed at the head end of the power distribution room (box), use an insulating rod-type clamp ammeter to reconfirm the serious leakage fault phase with a large value on the first base outlet pole, and keep this fault firmly in mind. Mutually. Then along the fault phase, measure and search step by step towards the power receiving side.
3. Search for T-word branches. When encountering T-shaped branch line measurement and search, take the T-shaped branch pole as the reference, first measure the main line A1 point (the direction of the power receiving side), and then measure the branch line A2 point. For example, the leakage value of the measurement point of the A1 main line is large, but there is no leakage display at the A2 point. Then it shows that the leakage fault point is still in the back section of the main line, not on the T-shaped branch line.
4. Search for cross branches. When measuring and looking for a cross branch line, take the cross branch pole as the reference, and first measure the point A1 of the main line (the direction of the power receiving side). If there is no leakage display, it means that the fault point is at point A2 (the "ten" side of the branch line) or A3 point (the "one" side of the branch line). If there is leakage current at points A2 and A3 at the same time, it means that there is a multi-point grounding fault. Find the leakage fault point step by step according to the principle that the current value is large first and then small. By analogy and step by step, the serious leakage fault point or user can be found soon. This method is also very fast and accurate for finding power theft from one line to one place.
